Injection molding valve flow control

ABSTRACT

Apparatus for controlling the rate of flow of fluid material through an injection molding flow channel leading to a mold cavity, the apparatus comprising:
         a pin having a longitudinal length and a diameter slidably mounted in an aperture in a housing that is adapted for back and forth axial movement of the pin through the flow channel;   the pin having a protrusion at a selected position along its length, the protrusion having an upstream end and a downstream end and a maximum diameter circumferential surface intermediate the upstream and downstream ends;   the channel having an interior surface area portion which is complementary to the maximum diameter circumferential surface of the protrusion of the pin;
 
the pin being slidable to a position within the channel such that the maximum diameter circumferential surface of the protrusion is matable with the complementary interior surface portion of the channel to stop flow of the fluid material.

RELATED APPLICATIONS

This is a continuation of and claims the benefit of priority of U.S.patent application Ser. No. 11/351,243 which is a continuation of U.S.patent application Ser. No. 10/328,457, filed Dec. 23, 2002 which claimsthe benefit of priority under 35 USC Section 119 to U.S. provisionalpatent application Ser. No. 60/399,409 filed Dec. 26, 2001, thedisclosures of all of the foregoing of which are incorporated herein byreference in their entirety as if fully set forth herein.

The disclosures of all of the following are also incorporated byreference in their entirety as if fully set forth herein: U.S. Pat. Nos.5,894,025, 6,062,840, 6,294,122, 6,309,208, 6,287,107, 6,343,921,6,343,922, 6,254,377, 6,261,075, 6,361,300, 6,464,909, U.S. patentapplication Ser. No. 10/214,118, filed Aug. 8, 2002 (7006), U.S. patentapplication Ser. No. 09/699,856 filed Oct. 30, 2000 (7056), U.S. patentapplication Ser. No. 10/269,927 filed Oct. 11, 2002 (7031), U.S.application Ser. No. 09/503,832 filed Feb. 15, 2000 (7053), U.S.application Ser. No. 09/656,846 filed Sep. 7, 2000 (7060), U.S.application Ser. No. 10/006,504 filed Dec. 3, 2001, (7068) and U.S.application Ser. No. 10/101,278 filed Mar. 19, 2002 (7070).

BACKGROUND OF THE INVENTION

Injection molding systems comprise an injection molding machine having abarrel and a screw (or ram) housed within a barrel which injects a fluidmaterial from an exit port of the barrel at a preselected velocity orprofile of velocities over an injection cycle into a flow channel orsystem of channels in a distribution manifold which, in turn, direct thefluid to one or more injection ports which lead to one or more cavitiesof one or more molds.

Apparati have been developed for controlling the rate of flow of fluidmaterial at a location within a flow channel, bore or nozzle having astraight axis that is aligned with the center of the gate of the moldcavity and along which a valve pin or other mechanical flow controllingmechanism is aligned for purposes of controlling material flow at thegate or at a position immediately upstream of the gate along the axisaligned with the gate. Such systems typically use an actuator mechanismthat is aligned with the axis that intersects the gate.

SUMMARY OF THE INVENTION

In accordance with the invention there is provided in an injectionmolding apparatus having upstream and downstream channels communicatingwith each other for delivering fluid material to one or more moldcavities, an apparatus for controlling delivery of the melt materialfrom the channels to the one or more mold cavities, each channel havingan axis, the downstream channel having an axis intersecting a gate of acavity of a mold, the upstream channel having an axis not intersectingthe gate and being associated with an upstream actuator interconnectedto an upstream melt flow controller disposed at a selected locationwithin the upstream channel, the apparatus comprising: a sensor forsensing a selected condition of the melt material at a positiondownstream of the upstream melt flow controller; an actuator controllerinterconnected to the upstream actuator, the actuator controllercomprising a computer interconnected to a sensor for receiving a signalrepresentative of the selected condition sensed by the sensor, thecomputer including an algorithm utilizing a value indicative of thesignal received from the sensor as a variable for controlling operationof the upstream actuator; wherein the upstream melt flow controller isadapted to control the rate of flow of the fluid material at theselected location within the upstream channel according to thealgorithm.

The apparatus can include a downstream melt flow controller movable by adownstream actuator between open flow and closed flow positions withinthe downstream channel. The downstream actuator is preferablyinterconnected to the actuator controller, the algorithm utilizing thevalue indicative of the signal received from the sensor as a variable tocontrol movement of the downstream melt flow controller between the openflow and closed flow positions.

The melt flow controller can be adapted to create a gap of controllablyvariable size within the upstream channel, the melt flow controllerbeing movable to increase the size of the gap and the rate of flow uponupstream movement of the melt flow controller. The melt flow controllercan movable to decrease the size of the gap and the rate of flow upondownstream movement of the melt flow controller.

The melt flow controller can comprises a pin having an axis slidablymounted for back and forth movement of the pin through the upstreamchannel; the pin having a bulbous protrusion along its axis, the bulbousprotrusion having a smooth surface extending between an upstream end anda downstream end of the bulbous protrusion and a maximum diametercircumferential surface intermediate the upstream and downstream ends ofthe bulbous protrusion; the complementary surface of the upstreamchannel being complementary to the maximum diameter circumferentialsurface of the bulbous protrusion of the pin; the pin being slidable toa position within the upstream channel such that the maximum diametercircumferential surface of the bulbous protrusion mates with thecomplementary interior surface portion of the upstream channel. The meltflow controller can comprise a rotary valve.

During an injection cycle having a start point, an end point and anintermediate time duration, the algorithm typically includes a first setof instructions for moving the downstream melt flow controller to theopen flow position at the start point and to the closed flow position atthe end point and a second set of instructions for moving the upstreamcontroller to a plurality of positions that control the rate of flow offluid material during the intermediate time duration, the first andsecond sets of instructions utilizing the value indicative of the signalreceived from the sensor as a variable for controlling operation of theupstream and downstream actuators.

In another aspect of the invention there is provided, an apparatus forcontrolling flow of a fluid material in an injection molding apparatushaving a flow channel system having an upstream flow channel having afirst axis through which fluid material is routed to a downstreamchannel having a second axis leading to an exit aperture to a moldcavity, the apparatus comprising: a first valve mechanism comprising anactuator drivably interconnected to a fluid material contacting memberdisposed within the upstream flow channel; the upstream channelcommunicating with and delivering fluid material to the downstreamchannel, the downstream channel delivering the fluid material to theexit aperture, the first and second axes of the upstream and downstreamchannels being non-coaxial; the fluid material contacting member havingan outer surface portion engageable with a complementary surface of aportion of the upstream flow channel to stop flow of the fluid material,the actuator being controllably drivable to drive the outer surfaceportion of the fluid material contacting member through a selected rangeof gap distance relative to the complementary surface of the upstreamflow channel; the fluid material having a rate of flow through the flowchannel system that varies according to the gap distance.

In another aspect of the invention there is provided, an apparatus forcontrolling flow of a fluid material in an injection molding apparatushaving a flow channel system having an upstream flow channel having anaxis through which fluid material is routed to a gate of a mold, theapparatus comprising: a first valve mechanism comprising a firstactuator drivably interconnected to a fluid material contacting memberdisposed within the upstream flow channel; the upstream channelcommunicating with and delivering fluid material to the, the gate of themold; the axis of the upstream channel being offset from and notintersecting the gate of the mold; the fluid material contacting memberhaving an outer surface portion engageable with a complementary surfaceof a portion of the upstream flow channel to stop flow of the fluidmaterial, the actuator being controllably drivable to drive the outersurface portion of the fluid material contacting member through aselected range of gap distance relative to the complementary surface ofthe upstream flow channel; the fluid material having a rate of flowthrough the flow channel system that varies according to the gapdistance.

There is also provided in accordance with the invention a method ofcontrolling fluid flow during an injection cycle in an injection moldingmachine having a fluid flow distribution system for delivering fluidmaterial to a gate of a mold, the method comprising: injecting fluidthrough an upstream channel having an axis not intersecting the gate ofthe mold; regulating the rate of flow of the fluid during the course ofthe injection cycle at a selected position within the upstream channelaccording to an algorithm which receives a variable input indicative ofa sensed condition of the fluid material sensed by a sensor during theinjection cycle; and routing the regulated flow of fluid from theupstream channel to a downstream channel having an axis intersecting thegate of the mold.

In the method, the selected condition of the fluid material can besensed by the sensor at a position in the flow channel system that isdownstream of the selected position in the upstream at which the flow isregulated.

In a preferred embodiment, the method can further comprise regulatingthe stopping and starting of flow of the fluid material in the injectioncycle at a position within the downstream channel. The regulating of thestopping and starting of flow is preferably carried out according to thealgorithm based on the variable input indicative of the sensedcondition.

The present invention further provides a fluid material flow controlapparatus which comprises a valve pin slidably disposed within a flowchannel having an exit aperture through which fluid material is injectedinto a mold cavity. The valve pin comprises an elongate pin which iscontrollably driven by a controllably drivable actuator in a reciprocalback and forth motion through the flow channel leading to the exitaperture. The valve pin has a bulbous protrusion or bulb or enlargeddiameter portion along its length wherein the bulbous protrusion has acontinuously smooth curvilinear exterior surface extending from anupstream end to a downstream end of the bulbous protrusion. The bulbousprotrusion has an intermediate cross-sectional sectional circumferentialsurface having a maximum diameter, at a selected position along theaxial length of the protrusion for mating with an interior surface ofthe channel having a complementary diameter to the maximum diameter ofthe bulbous protrusion. The mating of the bulb and complementary surfaceof the channel acts to stop fluid flow through the channel.

The complementary interior surface of the channel with which the maximumdiameter exterior circumferential surface of the bulbous protrusionmates is typically arranged/disposed within the channel as a straightrestricted throat section of the channel e.g. cylindrical inshape/geometry. The valve pin and the bulbous protrusion have a commonaxis. An upstream section of the valve pin is mounted within acomplementary aperture in a housing, hotrunner or manifold for slidablereciprocal back and forth movement along the axis of the pin. The pin ismounted such that the bulbous protrusion portion of the pin isreciprocally movable back and forth through a selected length of therestricted throat section of the channel. The intermediate maximumdiameter circumferential surface of the bulbous protrusion which mateswith the restricted throat section of the channel is complementary ingeometry to the throat section, typically comprising, for example, ashort straight surface on the exterior of the bulb (e.g. in the shape ofa cylinder) which matably slides along the complementary short straightsurface of the throat as the bulb is moved axially through the throat.When the maximum diameter circumferential surface of the bulb is movedout of mating contact with the interior surface of the throat, polymerfluid which is being fed under pressure through the channel is able topass through the throat section along a path toward the exit of thechannel where the polymer fluid first passes smoothly along the upstreamcontinuously curvilinear surface of the bulb and subsequently along thedownstream continuously curvilinear surface of the bulb.

The pin has a length selected such that the pin can be controllablydriven through at least a first position where polymer fluid flow isstopped when the maximum diameter circumferential surface of the bulbousprotrusion mates with the complementary throat surface, a seconddownstream position where polymeric fluid flow is enabled between theexterior curvilinear surface of the bulbous protrusion and the interiorsurface of the channel leading to the exit aperture of the nozzle and athird position where a terminal downstream end of the valve pin mateswith a complementary exit aperture surface to open and close theaperture.

The pin may alternatively have a selected length such that the terminaldownstream end of the pin does not engage or mate with any surface at ornear the exit aperture of the nozzle during the course of its drivenstroke and thus does not open and close the exit aperture of the nozzleat any time.

The pin is controllably movable/slidable via the actuator to any desiredintermediate flow position. In the intermediate flow positions the rateof polymeric fluid flow is varied depending on the axial distancebetween the maximum diameter circumferential surface of the bulbousprotrusion and the complementary mating throat surface, the fluid flowrate being greater, the greater the axial distance.

Most typically the actuator is driven according to a programmablycontrollable algorithm which receives variable inputs based on signalsreceived from one or more sensors which monitor one or more propertiesor conditions of the fluid polymeric material which is being injectedthrough the manifold/hotrunner and/or into the mold cavity. Sensing oneor more fluid properties such as pressure, temperature and fluid flowrate may be used to monitor the fluid and signals from such sensorsinput to the algorithm which control the drive of the actuator which inturn controls the position of the valve pin.

The curvilinear surfaces of the bulbous protrusion of the pin regulate asmooth transition of polymer fluid flow rate from upstream to downstreamalong the exterior curvilinear surface of the bulb as the bulb of thepin is moved axially through the channel either further away from orcloser toward the restricted throat section.

In accordance with the invention therefore there is provided anapparatus for controlling the rate of flow of fluid material through aflow channel having an exit aperture leading to a mold cavity, theapparatus comprising: a pin having an axis slidably mounted in a housingcontaining the channel for back and forth axial movement of the pinthrough the channel; the pin having a bulbous protrusion along its axis,the bulbous protrusion having a smooth curvilinear surface extendingbetween an upstream end and downstream end of the bulbous protrusion anda maximum diameter circumferential surface intermediate the upstream anddownstream ends of the bulbous protrusion; the channel having aninterior surface area portion which is complementary to the maximumdiameter circumferential surface of the bulbous protrusion of the pin;the pin being slidable to a position within the channel such that themaximum diameter circumferential surface of the bulbous protrusion mateswith the complementary interior surface portion of the channel.

The valve is drivable through at least a first position wherein polymerfluid flow is stopped when the maximum diameter circumferential surfaceof the bulbous protrusion mates with the complementary interior channelsurface and a second downstream or upstream position where polymer fluidflow is enabled between the curvilinear surface of the bulbousprotrusion and an interior surface of the channel. The valve ispreferably drivable through a third downstream position where a terminaldownstream end of the valve pin mates with a complementary exit aperturesurface to stop fluid flow.

The maximum diameter circumferential surface of the bulbous protrusionis preferably cylindrical in shape and the complementary interiorsurface portion of the channel is preferably cylindrical in shape.

The pin is slidably mounted in the housing in an aperture which may havea diameter equal to or greater than the diameter of the maximum diametercircumferential surface of the bulbous protrusion of the pin.

Further in accordance with the invention there is provided, in aninjection molding machine having at least one nozzle for delivering meltmaterial from a manifold to a mold cavity, apparatus for controllingdelivery of the melt material from the nozzle to the mold cavity, thenozzle having an exit aperture communicating with a gate of the cavityof the mold and being associated with an actuator interconnected to amelt flow controller, the apparatus comprising: a sensor for sensing aselected condition of the melt material through the nozzle; an actuatorcontroller interconnected to the actuator, the actuator controllercomprising a computer interconnected to a sensor for receiving a signalrepresentative of the selected condition sensed by the sensor, thecomputer including an algorithm utilizing a value corresponding to asignal received from the sensor as a variable for controlling operationof the actuator; wherein the actuator is interconnected to and controlsmovement of a pin having a bulbous protrusion, the pin and the bulbousprotrusion having a common axis, the pin being slidably mounted in achannel leading to the gate for back and forth movement axial movementof the bulbous protrusion through the channel; wherein the bulbousprotrusion has a maximum cross-sectional diameter section having anexterior surface which is matable with a complementary interior wallsurface section of the channel at a selected position along the back andforth axial movement of the bulbous protrusion through the channel.

The at least one nozzle preferably has a seal surface on a tip end ofthe nozzle, the nozzle being expandable upon heating to a predeterminedoperating temperature, the nozzle being mounted relative to acomplementary surface surrounding the gate such that the seal surfacedisposed on the tip end of the nozzle is moved into compressed contactwith the complementary surface surrounding the gate upon heating of thenozzle to the predetermined operating temperature. The tip end of thenozzle may comprise an outer unitary piece formed of a first materialand an inner unitary piece formed of a second material, the firstmaterial being substantially less heat conductive than the secondmaterial.

The sensor typically comprises a pressure transducer interconnected toat least one of the bore of a nozzle or a mold cavity for detecting thepressure of the melt material. The actuator controller typically furthercomprises a solenoid having a piston controllably movable betweenselected positions for selectively delivering a pressurized actuatordrive fluid to one or the other of at least two chambers of theactuator.

The exterior surface of the maximum diameter section of the bulbousprotrusion may form a gap between the exterior surface of the bulbousprotrusion and the complementary surface of the channel upon axialmovement of the pin to a position where the exterior surface of thebulbous protrusion and the complementary surface of the channel are notmated, wherein the size of the gap is increased when the valve pin isretracted away from the gate and decreased when the valve pin isdisplaced toward the gate. Alternatively, the exterior surface of themaximum diameter section of the bulbous protrusion forms a gap betweenthe exterior surface of the bulbous protrusion and the complementarysurface of the channel upon axial movement of the pin to a positionwhere the exterior surface of the bulbous protrusion and thecomplementary surface of the channel are not mated, wherein the size ofthe gap is decreased when the valve pin is retracted away from the gateand increased when the valve pin is displaced toward the gate.

At least one of the valves may have a bore and a valve pin, theapparatus further comprising a plug mounted in a recess of the manifoldopposite a side of the manifold where the at least one nozzle iscoupled, the plug having a bore through which a stem of the valve pin ofthe nozzle passes, the valve pin having a head, the bore of the plugthrough which the stem passes having a smaller diameter than the valvepin head at the valve pin head's largest point and the recess of themanifold having a larger diameter than the diameter of the valve pinhead at the valve pin head's largest point, so that the valve pin can beremoved from the manifold from a side of the manifold in which therecess is formed when the plug is removed from the manifold.

The apparatus may further comprise a second sensor for sensing a secondselected condition of the melt material through a second nozzle, thecomputer being interconnected to the second sensor for receiving asignal representative of the selected condition sensed by the secondsensor, the computer including an algorithm utilizing a valuecorresponding to a signal received from the second sensor as a variablefor controlling operation of an actuator for the second nozzle.

The seal surface of the at least one nozzle is preferably a radiallydisposed surface which makes compressed contact with the complementarysurface of the mold surrounding the gate. The seal surface of the atleast one nozzle is typically a longitudinally disposed tip end surfacewhich makes compressed contact with the complementary surface of themold surrounding the gate.

The sensor is preferably selected from the group consisting of apressure transducer, a load cell, a valve pin position sensor, atemperature sensor, a flow meter and a barrel screw position sensor.

The pin is most preferably mounted in an aperture in a housingcontaining the channel, the aperture having a diameter equal to orgreater than the maximum diameter circumferential surface of the bulbousprotrusion of the pin.

Apparatus for controlling the rate of flow of fluid material through aninjection molding flow channel leading to a mold cavity, the apparatuscomprising:

-   -   a pin having a longitudinal length and a diameter slidably        mounted in an aperture in a housing that is adapted for back and        forth axial movement of the pin through the flow channel;    -   the pin having a protrusion at a selected position along its        length, the protrusion having an upstream end and a downstream        end and a maximum diameter circumferential surface intermediate        the upstream and downstream ends;    -   the channel having an interior surface area portion which is        complementary to the maximum diameter circumferential surface of        the protrusion of the pin;    -   the pin being slidable to a position within the channel such        that the maximum diameter circumferential surface of the        protrusion is matable with the complementary interior surface        portion of the channel to stop flow of the fluid material.

The pin is preferably drivable through at least a first position whereinfluid flow is stopped when the maximum diameter circumferential surfaceof the protrusion mates with the complementary interior channel surfaceand a second downstream or upstream position where fluid flow is enabledbetween either the upstream or downstream end of the protrusion and thecomplementary interior channel surface of the channel.

The contour of the protrusion at the upstream or downstream end of theprotrusion is typically curvilinear.

The pin can be adapted to be drivable through at least a first positionwherein fluid flow is stopped when the maximum diameter circumferentialsurface of the protrusion mates with the complementary interior channelsurface and a second upstream position where fluid flow is enabledbetween the downstream end of the protrusion and the complementaryinterior channel surface of the channel and a third downstream positionwhere fluid flow is enabled between the upstream end of the protrusionand the complementary interior channel surface of the channel.

The pin can be adapted to be drivable through a downstream positionwhere a terminal end of the pin downstream of the protrusion mates witha complementary exit aperture of the channel that is immediatelyadjacent to an entrance port to the mold.

The maximum diameter circumferential surface of the bulbous protrusionis typically cylindrical in shape.

The complementary interior surface portion of the channel is typicallycylindrical in shape.

The aperture in the housing in which the pin is slidably mountedpreferably has a diameter equal to or greater than the maximum diametercircumferential surface of the protrusion of the pin.

The complementary interior surface portion of the channel is preferablydisposed upstream of a gate area of the mold, the pin being adapted toselectively position the protrusion relative to the complementaryinterior surface portion of the channel such that the rate of flow ofthe fluid is controllably varied.

The apparatus can further comprise:

-   -   a sensor for sensing a selected condition of the fluid;    -   a computer interconnected to the sensor for receiving a signal        representative of the selected condition sensed by the sensor,    -   the computer including an algorithm utilizing a value        corresponding to the signal received from the sensor as a        variable for controlling operation of an actuator that is        drivably interconnected to the pin.

The pin typically comprises a first portion having a diametercomplementary to the aperture in the housing and a second portioninterconnecting the first portion and the protrusion, the second portionhaving a maximum diameter that is less than the diameter of the firstportion and the maximum diameter of the protrusion.

Further in accordance with the invention there is provided a method ofcontrolling the rate of flow of fluid through a flow channelcommunicating with a gate of a mold in an injection molding apparatus,the apparatus including a valve pin having a selected longitudinallength that is slidably mounted in a housing that is adapted for backand forth axial movement of the pin through the flow channel, the methodcomprising:

-   -   forming the pin with a protrusion at a selected position along        its length such that the protrusion is movable back and forth        within the channel wherein the protrusion has an upstream end        and a downstream end;    -   forming the protrusion with a maximum diameter outer        circumferential surface between its upstream and downstream        ends;    -   forming the channel with an interior surface area portion which        is complementary to the maximum diameter circumferential surface        such that the maximum diameter outer circumferential surface of        the protrusion is matable with the interior surface area portion        of the channel to stop flow of the fluid through the channel;    -   controlling movement of the pin through the channel to        selectively position the maximum diameter circumferential        surface of the protrusion at controllably selectable positions        relative to the interior surface area portion of the channel        such that the rate of flow of the fluid through the channel is        controllably variable.

The method is preferably implemented such that the complementaryinterior surface area portion of the channel is disposed at a positionupstream of and away from the gate of the mold.

The method typically further comprises controlling movement of the pinto position the downstream end of the protrusion at controllablyselectable distances relative to the interior surface area portion ofthe channel such that the rate of flow of fluid between the downstreamend and the interior surface area portion is controllably variable.

The method can further comprise controlling movement of the pin toposition the upstream end of the protrusion at controllably selectabledistances relative to the interior surface area portion of the channelsuch that the rate of flow of fluid between the downstream end and theinterior surface area portion is controllably variable.

The method can further comprise:

-   -   sensing a selected condition of the fluid;    -   controlling movement of the pin within the channel according to        an algorithm that determines a position for movement of the pin        based on the use as a variable of a value indicative of the        selected condition of the fluid that is sensed in the step of        sensing.

The method can further comprise:

-   -   forming the aperture in the housing in which the pin is slidably        mounted and the pin to have a diameter equal to or greater than        the maximum diameter circumferential surface of the protrusion        of the pin.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and further advantages of the invention may be betterunderstood by referring to the following description in conjunction withthe accompanying drawings in which:

FIG. 1 is a partially schematic cross-sectional view of an injectionmolding system used in one embodiment of the present invention;

FIGS. 1A-C are schematic representations of gates to a single mold andto molds of different sizes;

FIG. 2 is an enlarged fragmentary cross-sectional view of the valve pinsused as flow contacting and flow rate controlling members in the FIG. 1system;

FIG. 3 is a partially schematic, plan sectional view of a systemaccording to the invention;

FIG. 4 is a sectional, partially schematic view of the FIG. 3 system;

FIG. 5 is an enlarged fragmentary view of the valve pins used as flowcontacting and flow rate controlling members in the FIG. 3 system;

FIGS. 6-8 are enlarged, fragmentary views of an alternative valve pinusable as a flow contacting and flow rate controlling member in the FIG.1 and FIG. 3 systems;

FIGS. 9-11 are examples of displays that can be displayed on a userinterface, the user interface being interconnected to a master computercontroller as shown and described with reference to the FIGS. 1, 3embodiments;

FIG. 12 is a side cross-sectional view of a shaftless motor for use asan alternative actuator for flow control mechanism in accordance withthe invention, the motor having an axially movable screw for driving theflow controller; and,

FIG. 13 is a schematic side cross-sectional view of a rotary valve flowcontroller system.

FIG. 14 is a side cross-sectional view of valve having a curvilinearbulbous protrusion and an extended pin, the bulbous protrusion being ina flow shut-off position;

FIG. 14A is a close-up view of the bulbous protrusion of FIG. 32;

FIG. 15 is a view similar to FIG. 32 showing the bulbous protrusion in aflow controlling position;

FIG. 15A is a close-up view of the bulbous protrusion position of FIG.33;

FIG. 16 is a view similar to FIG. 32 showing the bulbous protrusion in adownstream position and the distal tip end of the extended pin in a gateflow shut-off position;

FIG. 16A is a close-up view of the bulbous protrusion position of FIG.34;

FIG. 17 is a side cross-sectional view of valve having a curvilinearbulbous protrusion, the bulbous protrusion being in a flow shut-offposition and not having a gate shut off distal pin extension section;

FIG. 18 is a view similar to FIG. 35 showing the bulbous protrusion in aflow controlling position;

FIG. 19 is a side cross-sectional view of valve having a curvilinearbulbous protrusion, where the pin is mounted in an aperture in the hotrunner which has a diameter equal to the diameter of the bulbousprotrusion such that the pin may be withdrawn from the actuator and thehotrunner without removing the actuator from the housing or the mountingbushing from the hotrunner, and where the bulbous protrusion is in aflow shut-off position;

FIG. 19A is a close-up view of the bulbous protrusion in the flow shutoff position of FIG. 37;

FIG. 20 is a view similar to FIG. 37 showing the bulbous protrusion in adownstream flow controlling position;

FIG. 20A is a close-up view of the bulbous protrusion in the flowcontrolling position of FIG. 38;

FIG. 21 is a schematic side cross-sectional view of an embodiment of apin having a bulbous protrusion with a maximum diameter circumferentialsection which has straight surfaces, e.g. cylindrical, whichcomplementarily mate with a complementary straight cylindrical surfaceon the interior of the flow channel at a throat section;

FIG. 22 is a schematic side cross-sectional view of an embodimentshowing a bulbous protrusion similar to FIG. 39 but where thecontrolling flow position is upstream of the throat section of thechannel and the flow shut-off position is achieved or reached by forwardor upstream movement of the pin from the position shown in FIG. 40.

DETAILED DESCRIPTION

FIG. 1 shows one embodiment of an injection molding system 10 accordingto the present invention having a valve gated nozzle 192 and a thermalgated nozzle 202 delivering fluid material to gates 178 and 188respectively, which in turn communicate with and deliver fluid materialto mold cavities 170 and 180 respectively. Fluid material is injectedinitially under pressure from injection molding machine barrel 120 intoa main injection channel 14 formed in heated manifold 12 and travelsfrom channel 14 to common upstream feed channel 160. Channel 160 feedsand communicates with downstream channels 162 and 164 having axes 163,165 via intermediate upstream channels formed within bushings 108, 118having axes 104, 114 respectively. The intermediate upstream channels orbores formed within upstream bushings 108, 118 communicate withdownstream channels 190, 200 respectively via upstream channels 162, 164as shown. The downstream channels 190, 200 comprise, in part, boresformed within downstream nozzles/bushings 192, 202 respectively that aredisposed at the distal most ends of downstream channels 190, 200. Thedownstream channels 190, 200 have axes 175, 185 respectively that arealigned with and intersect gates 178, 188 respectively. As shown, theupstream channels 162, 164, the upstream channels formed within bushings108, 118 and the upstream channel 160 all have axes which are offsetfrom the axes of downstream channels 190, 200 are not coaxial with axes175, 185 and do not intersect gates 178, 188. Although only two nozzlesare shown in FIG. 1, the invention contemplates simultaneouslycontrolling the material flow through a plurality of more than twonozzles to a plurality of gates. In the embodiment shown, the injectionmolding system 10 is a two mold cavity 170, 180 system. The presentinvention can be adapted to any of a variety of systems where severaldownstream channels 183, 185 feed a single uniformly dimensioned cavity181 in a symmetrical arrangement, FIG. 1A, or where several channels193, 195 feed separate cavities 199, 197 of differentsize/configuration, FIG. 1B, or where several channels 206, 207 feed asingle non-uniform cavity 208 at different locations/points of entrywhere the volumes to be filled 208 a, 208 b at entry are different, FIG.1C.

A system according to the invention is typically used to inject plasticmaterial which is heated/melted to a fluid form and injected through aheated manifold 12 which maintains the plastic material in fluid form.The invention is also applicable to other types of injection systems inwhich it is useful to control the rate at which another fluid material,e.g., metallic or composite materials is delivered to a cavity of amold.

The rate at which fluid material is delivered through the channels ofthe FIG. 1 embodiment is controllably varied by the fluid contactingmembers 102, 112 which are controllably movable along axes 104, 114 intoand out of engagement contact with a complementary mating surface 103,113, respectively formed within bushings 108, 118. As shown in greaterdetail in FIG. 2 the fluid contacting member 102 comprises an enlargedbulbous protrusion 102 formed at the distal end of a valve pin 107 whichis interconnected at a proximal end to an actuator 40 which is in turninterconnected to a servocontroller 100 which is in turn interconnectedto a master controller 20 which typically comprises a computer or otherdigital data processing mechanism containing a program that executes oneor more algorithms that use one or more variables indicative of a signalreceived from one or more sensors 60, 80, 130 that sense a selectedcondition of the fluid material flowing through the various channels orbores of the system 10. As shown in the FIG. 1 embodiment, actuator 40,pin 107 and member 102 control fluid flow from common upstream channel160 to a valve gated downsteam channel 190 while a actuator 30, pin 117,member 112, servomechanism 110 control flow to a thermal gated channel200.

The master computer or controller 20 receives signal inputs indicativeof a fluid material condition from three sensors 60, 80 and 130 in theFIG. 1 system. All of the sensors as shown in FIG. 1 sense a conditionof the fluid at a location or position that are downstream of thelocation at which fluid rate controlling members 102, 112 arepositioned. In a preferred embodiment, the algorithm of the computer 20includes instructions for controlling the movement of actuator 40 andpin 102 to control the rate of fluid flow during an injection cyclethrough a gap 102 g, FIG. 2 that is controllably variable in size viacontrolled movement of pin 107 along axis 104. The algorithm alsoincludes instruction for controlling the opening and closing of gate 178during the same injection cycle via controlled movement of pin 195 alongaxis 175 between gate open and gate closed positions. Pin 195 closesgate 178 off by engagement of the distal end of pin 195 with acomplementary receiving aperture at the end of nozzle 192 thatcommunicates with mold cavity 170.

As shown in FIG. 2, the fluid contacting member 102 has a surface 102 swhich is complementary to a mating surface 103 within the flow channel.When the two surfaces mate, i.e. when the member 102 is in the position102 p in dashed lines in FIG. 2, flow is stopped. Between the 102 pposition and the solid line 102 position shown in FIG. 2, the gap 102 gvaries in size and the rate of fluid flow varies depending on the sizeof the gap. In the FIGS. 1, 2 embodiment, the fluid flow rate decreaseson forward upstream movement 107 u of the valve pin 107 and actuator 40.Conversely, fluid flow rate increases on backward downstream movement107 d of pin 107. Pin 117, member 112, surface 113 and actuator 30function in the same manner as their analogous components describedabove on upstream 117 u and downstream 117 d movement of pin 117, member112 and actuator 30.

Upstream movement of a fluid contacting member, pin or the like meansthat the member moves against/in the opposite direction of the flow ofthe fluid. Downstream movement means that the member moves in the samedirection as the flow of fluid. Upstream movement to decrease and/orstop flow rate is preferred, at least when using the pin embodiments ofFIGS. 1-5.

FIG. 3 shows an embodiment with two upstream channels within bushings108 a, 118 a having control pins 107 a and 117 a respectively. Each ofvalve pins 108 a and 118 a separately controls fluid flow rate to a pairof downstream channels and gates (one downstream gate and nozzle shown,200 c, FIG. 4). Each of the downstream gates is controlled by a valvesimilar to the valve arrangement shown in FIG. 4 for controlling thestart and flow stop points of an injection cycle. As shown in FIG. 3each gate is associated with an actuator 50 a, 50 b, 50 c, 50 d which isinterconnected to a valve pin such as pin 200 a, FIG. 4, which opens andcloses a gate, e.g. gate 200 c leading to a mold cavity.

Valve pins 107 a, 117 a are mechanically interconnected to respectivehydraulic actuators 40 a, 30 a which are in turn interconnected toservomechanisms 100 a which are in turn controlled by computer 20 a.Computer 20 a includes an algorithm which utilizes a value indicative ofa signal received from downstream sensors 60 a, 80 a which sense aselected condition of the fluid material at a position downstream of thelocation of the point of fluid flow rate control, i.e. surfaces 103 a,113 a within bushings 108 a, 118 a. The algorithm controls the operationof actuators 40 a, 30 a which in turn control axial movement of pins 107a, 117 a and their associated enlarged fluid contacting members 102 a,112 a within the bores of bushings 108 a, 118 a. FIG. 5 shows in greaterdetail a configuration of a fluid contacting member 102 a.

As shown in FIG. 5, pin 107 a is movable in an upstream direction 107 uand downstream direction 107 d along axis 104 a. The upstream movementof pin 107 a is accomplished by backward movement of actuator 40 a asopposed to forward movement of actuators 40, 30 in the FIG. 1embodiment. A contoured surface 102 o of pin protrusion 102 a isconfigured to be complementary with channel surface 103 a such thatsurfaces 102 o and 103 a may mate upon complete upstream withdrawal ofpin 107 a whereby flow is stopped. As shown a gap 103 c between surfaces102 o and 103 a can be controllably varied in size depending on theposition of pin 107 a along axis 104 a. Upstream movement, 107 u, 117 uof pins 107 a and 117 a causes a gap such as gap 103 c to decrease insize and thus decrease the rate of fluid flow 109 a from common upstreamchannel 160 a to channels 162 a, 167. Conversely, downstream movement107 d, 117 d of pins 102 a, 112 a causes the gap, e.g. gap 103 c, toincrease in size and thus increase fluid flow rate. As shown, mainbarrel channel 120 feeds upstream channel 160 a which commonly feeds thebores or channels within bushings 108 a, 118 a. The flow from bushings108 a, 118 a feeds intermediate downstream channels 162 a, 164 a whichfeed intermediate channels 167, 169. Intermediate downstream channels167, 169 commonly feed the bores/channels associated with actuators 50a-d, e.g. bore 200 a, FIG. 4, all of which have an axis, e.g. 200 x,which intersect and lead to gates, e.g. gate 200 c, and their associatedmold cavities. As shown in FIG. 4, common feed channel 169 communicateswith a lateral channel 177 provided in bushing 202 a which communicateswith the bore/channel 200 a within bushing 202 a.

In both of the embodiments of FIGS. 1, 2 and FIGS. 3-5, the rate of flowis decreased by upstream movement of the fluid contacting member andincreased by downstream movement. As shown, the position at which fluidflow rate is controlled is located within a channel, having an axis,e.g. 104 a, 114 a, FIG. 4, which is not coaxial with the downstreamchannels having an axis that intersects a gate leading to a mold, e.g.channel 200 a having axis 200 x intersecting gate 200 c, FIG. 4.

FIGS. 6-8 show an alternative melt flow controller embodiment for use inthe invention. As shown, pin 107 t is slidably mounted in a mountingchannel 108 m having a diameter equal to the maximum diameter ofmidsection, 102 m of the fluid contacting member 102 t such that the pin107 t can be entirely withdrawn in the direction 107 u from the manifoldand bushing 108 t and readily replaced without disassembling any portionof the manifold or bushing 108 t. The maximum diameter midsection 102 mhas the same diameter as the complementary flow restricting throatsurface 103 s of the bushing 108 t such that when the two surfaces mateflow is stopped. As shown in FIGS. 7 and 8, the rate of flow and thesize of the flow rate determining gap 103 g can be controllably variedby either upstream movement 107 u, FIG. 8 or downstream movement, 107 d,FIG. 7 of pin 107 t. Upstream movement 107 u can form gap 103 g betweenbushing surface 108 g, FIG. 8, and the lower outer surface of member 102t. Downstream movement 107 d, FIG. 7, can also form a gap 103 g betweenchannel surfaces 103 s, 108 g and the upper portion of the outer surfaceof member 102 t. As described above, controlled movement of pin 107 t bycomputer 20 controls the size of the gap 103 g and thus the rate of flowfrom upstream channel 160 to downstream channel 162 t which leads todownstream channel 190 or 200 or the like. Axis x as shown in FIGS. 6-8corresponds to axis 104 of FIG. 1 and is not coaxial with axis 175 ofthe downstream bore 190 leading to a gate such as 175.

In the embodiments shown, a pressure sensor is typically used to sensethe pressure of the fluid material in the channel locations showndownstream of the upstream flow control members. In operation, theconditions sensed by the pressure transducer associated with eachchannel are fed back to a control system that typically includes PIDalgorithmic controllers (proportional, integral, derivative). Thecomputer 20 typically executes a proportional, integral, derivativealgorithm which compares the sensed pressure (at a given time) from thepressure transducer to a programmed target pressure (for the giventime). The computer 20 instructs the PID controller to adjust theposition of the flow controller or valve pin using the actuators inorder to mirror the target pressure for that given time. In this way aprogrammed target pressure or profile of pressure versus time (describedin detail below) for an injection cycle for a particular part for eachdownstream channel or gate can be followed by the computer or controller20.

As to each separate downstream channel leading to a gate, the targetpressure or pressure profile may be different, particularly where thechannels are injecting into separate cavities, and thus separatealgorithms or programs for achieving the target pressures at each nozzlemay be employed. As can be readily imagined, a single computer or CPUmay be used to execute multiple programs/algorithms for each channelleading to a gate or separate computers may be utilized.

Other sensed conditions can be used which relate to melt flow rate otherthan pressure. For example, the position of a melt flow controller orvalve pin or the load on the valve pin could be the sensed condition. Ifso, a position sensor or load sensor, respectively, could be used tofeed back the sensed condition to the PID controller.

The embodiments described control the rate of melt flow away from thegate along a channel axis offset from a channel having an axisintersecting and leading to a gate thus enabling control of flow rate tomultiple channels intersecting multiple gates. Controlling the melt flowaway from the gate also enables a pressure or other material conditionsensor to be located away from a gate.

In practical operation, a target profile of the condition of the fluidmaterial over the period of time of an injection cycle is created foreach downstream channel where a sensor is located. To create a targetprofile for a particular and the mold cavity associated therewith, theinjection molding machine is first set at maximum injection pressure andscrew speed, and parameters relating to the injection pressure,injection time, pack and hold pressure and pack and hold time are set onthe computer 20 at values that the molder estimates will generate goodparts based on part size, shape, material being used, experience, etc.Trial and error injection cycles are run for the selected channels andtheir associated, e.g. for channels 190, 200 and their associated moldcavities 170, 180, with alterations being made to the above parametersdepending on the condition of the parts to be produced. When the mostsatisfactory parts are produced during a trial injection cycle run, theprofile of fluid material condition that produced the most satisfactoryparts is determined for those particular channels or nozzle bores andthe cavities associated therewith. This process is repeated for allchannels in which a sensor is mounted until target fluid conditionprofiles are ascertained for each channel having a sensor and cavityassociated therewith. Preferably, the predetermined ideal targetprofiles are stored in computer 20 and used by the computer forcontrolling servomechanisms 100, 110 and 115 during actual productioninjection cycles.

The foregoing process of ideal profile creation can be used with anynumber of channels having a sensor. Although it may be preferable toprofile one channel and associated cavity at a time (while the otherchannels are closed) in a “family tool” mold application, the targetprofiles can also be created by running all channels simultaneously, andsimilarly adjusting each channel profile according to the quality of theparts produced. This would be preferable in an application where all thechannels are injecting into like cavities, since the profiles should besimilar, if not the same, for each channel and its associated cavity.

In single cavity applications (where multiple channels from a manifoldare injecting into a single cavity), the target profiles can also becreated by running the channels at the same time and adjusting theprofiles for each channel according to the quality of the part beingproduced.

The system can be implemented using a user interface 214, FIGS. 9 a-b inwhich each target profile can be stored, displayed and sent as an inputto the algorithm to be executed by the computer/controller 20.Alternatively the profile data can be input to and stored directly inthe computer without the interface.

FIGS. 9 a-b show one example of pressure versus injection cycle timegraphs (235, 237) of the pressure detected by the two pressuretransducers 60 a, 80 a associated with the two channels 167, 169. Thegraphs of FIGS. 9 a-b are generated and/or displayed on the userinterface 214 so that a user can observe the tracking of the actualpressure during an actual injection cycle versus the target pressureduring the course of an actual injection cycle in real time, or afterthe cycle is complete. The two different graphs of FIGS. 9 a and 9 bshow two independent target pressure profiles (“desired”) emulated bythe two channels 167, 169. Different target profiles may be desirable touniformly fill different sized mold cavities associated with eachchannel that is associated with actuators 50 a-d, or to uniformly filldifferent sized sections of a single cavity. Profiles such as these canbe generated with respect to any embodiments of the invention.

The melt flow controller, 102 a associated with graph 235 is openedsequentially at. 5 seconds after the melt flow controller 112 aassociated with graph 237 is opened at. 00 seconds. During injection(for example,. 00 to 1.0 seconds in FIG. 9 b) and pack and hold (forexample, 1.0 to 6.25 seconds in FIG. 9 b) portions of the graphs, eachmelt flow controller 102 a, 112 a (or fluid contacting member) iscontrollably moved to a plurality of positions to alter the pressuresensed by the pressure transducers 60 a, 80 a to track the targetpressure profiles.

Through the user interface 214, target profiles can be designed, andchanges can be made to any target profile using standard windows-basedediting techniques.

The profiles are then used by computer 20 to control the actuators 50a-d and thus control the position of the valve pins 107 a and 117 a. Forexample, FIG. 10 shows an example of a profile creation and editingscreen icon 300 generated on interface 214.

Screen icon 300 is generated by a windows-based application performed oninterface 214. Alternatively, this icon could be generated on aninterface associated with controller 20. Screen icon 300 provides a userwith the ability to create a new target profile or edit an existingtarget profile for any given nozzle and cavity associated therewith.

A profile 310, FIG. 10, includes (x, y) data pairs, corresponding totime values 320 and pressure values 330 which represent the desiredpressure sensed by the pressure transducer for the channel beingprofiled. The screen icon shown in FIG. 10 is shown in a “basic” mode inwhich a limited group of parameters are entered to generate a profile.For example, in the foregoing embodiment, the “basic” mode permits auser to input start time displayed at 340, maximum fill pressuredisplayed at 350 (also known as injection pressure), the start of packtime displayed at 360, the pack and hold pressure displayed at 370, andthe total cycle time displayed at 380.

The screen also allows the user to select the particular melt flowcontroller they are controlling displayed at 390, and name the partbeing molded displayed at 400. Each of these parameters can be adjustedindependently using standard windows-based editing techniques such asusing a cursor to actuate up/down arrows 410.

By clicking on a pull-down menu arrow 391, the user can select differentchannel melt flow controllers in order to create, view or edit a profilefor the selected channel and cavities associated therewith. Also, a partname 400 can be entered and displayed for each selected channel flowcontroller.

The newly edited profile can be saved in computer memory individually,or saved as a group of profiles for a group of channels that inject intoa particular single or multicavity mold. The term “recipe” is used todescribe a group of profiles for a particular mold and the name of theparticular recipe is displayed at 430 on the screen icon.

To create a new profile or edit an existing profile, first the userselects a particular channel for the particular recipe being profiled.The flow controller selection is displayed at 390. The user inputs analpha/numeric name to be associated with the profile being created, forfamily tool molds this may be called a part name displayed at 400. Theuser then inputs a time displayed at 340 to specify when injectionstarts. A delay can be with particular channel controllers to sequencethe opening of the valves and the injection of melt material intodifferent gates of a mold.

The user then inputs the fill (injection) pressure displayed at 350. Inthe basic mode, the ramp from zero pressure to max fill pressure is afixed time, for example, 3 seconds. The user next inputs the start packtime to indicate when the pack and hold phase of the injection cyclestarts. The ramp from the filling phase to the packing phase is alsofixed time in the basic mode, for example, at about 0.3 seconds.

The final parameter is the cycle time which is displayed at 380 in whichthe user specifies when the pack and hold phase (and the injectioncycle) ends. The ramp from the pack and hold phase to zero pressure atabout 16.5 seconds will be instantaneous when a valve pin (e.g. 195) asin the FIGS. 1-5 embodiments is used to close a gate, or slower in athermal gate (e.g. FIG. 1, nozzle 202) due to the residual pressure inthe cavity which will decay to zero pressure once the part solidifies inthe mold cavity. The “cool” time typically begins upon the drop to zeropressure and lasts to the end of the cycle, e.g. 16.5-30.0 seconds inFIG. 10.

User input buttons 415 through 455 are used to save and load targetprofiles.

Button 415 permits the user to close the screen. When this button isclicked, the current group of profiles will take effect for the recipebeing profiled. Cancel button 425 is used to ignore current profilechanges and revert back to the original profiles and close the screen.Read Trace button 435 is used to load an existing and saved targetprofile from memory. The profiles can be stored in memory contained inthe interface 215 or the controller 210. Save trace button 440 is usedto save the current profile. Read group button 445 is used to load anexisting recipe group. Save group button 450 is used to save the currentgroup of target profiles for a group of flow controllers. The processtuning button 455 allows the user to change the PID settings (forexample, the gains) for a particular channel valve in a control zone.Also displayed is a pressure range 465 for the injection moldingapplication.

Button 460 permits the user to toggle to an “advanced” mode profilecreation and editing screen. The advanced profile creation and editingscreen is shown in FIG. 11.

The advanced mode allows a greater number of profile points to beinserted, edited, or deleted than the basic mode. As in the basic mode,as the profile is changed, the resulting profile is displayed.

The advanced mode offers greater profitability because the user canselect values for individual time and pressure data pairs. As shown inthe graph 420, the profile 470 displayed is not limited to a singlepressure for fill and pack/hold, respectively, as in the basic mode. Inthe advanced mode, individual (x, y) data pairs (time and pressure) canbe selected anywhere during the injection cycle.

To create and edit a profile using advanced mode, the user can select aplurality of times during the injection cycle (for example 16 differenttimes), and select a pressure value for each selected time. Usingstandard windows-based editing techniques (arrows 475) the user assignsconsecutive points along the profile (displayed at 478), particular timevalues displayed at 480 and particular pressure values displayed at 485.

The next button 490 is used to select the next point on the profile forediting. Prev button 495 is used to select the previous point on theprofile for editing. Delete button 500 is used for deleting thecurrently selected point. When the delete button is used the twoadjacent points will be redrawn showing one straight line segment.

The add button 510 is used to add a new point after the currentlyselected point in which time and pressure values are entered for the newpoint. When the add button is used the two adjacent points will beredrawn showing two segments connecting to the new point.

Sensors which detect properties other than pressure may be employed.Preferably, sensors are used which detect a property of the fluid or ofthe operation of the mechanisms that control fluid flow rate. Dataindicative of flow rate typically comprises a fluid property that isreadily correlatable to or convertible by an algorithm to the time orrate of filling of the mold cavity. Fluid pressure leading to or throughan injection port is one example of flow rate data. The position of amechanical flow controller mechanism such as a valve pin, rotary valve,plunger or ram; the position of an actuator that can be used to controlmovement of a pin, rotary valve, plunger or ram; the force or pressureexerted by an actuating mechanism (e.g. hydraulic, pneumatic actuator),electric motor, ram or the like; the electrical power or hydraulic orpneumatic pressure that is used to drive an actuating mechanism, motor,ram or the like during an injection cycle are other examples of datathat a sensor can record and be converted to a variable for input to analgorithm executable by a computer 20, 20 a for controlling the movementof a melt flow controller or fluid contacting member.

Following is a list of exemplary flow rate indicative parameters that asensor can be used to detect for use in the invention:

-   -   position of a flow controlling valve pin or actuator cylinder;    -   force or pressure exerted on or by a flow controlling valve pin,        actuator cylinder, ram, screw or motor;    -   energy or power used to operate a flow controlling actuator,        ram, motor or the like;    -   flow rate recorded by a mechanical, optical or electronic        sensing flowmeter;    -   flow volume injected over time by a machine ram/screw;    -   velocity of movement of a flow controlling component such as        valve pin, alternative ram, plunger, rotary valve or the like.

As described with respect to the FIGS. 9-11 profile of fluid pressuredata, a similar profile of data for any of the above variables over thetime of an injection cycle may be obtained by trial and error running ofan injection molding apparatus and then used as a target profile to beemulated by an algorithm to control the movement of a melt flowcontroller during an injection cycle.

FIG. 12 shows an example of an electrically powered motor which may beused as an actuator 301, in place of a fluid driven mechanism (such as30, 40, 30 a, 40 a, FIGS. 1, 3) for driving a valve pin or rotary valveor other nozzle flow control mechanism. In the embodiment shown in FIG.12 a shaftless motor 300 a mounted in housing 302 has a center ball nut304 in which a screw 306 is screwably received for controlled reciprocaldriving 308 of the screw 308 a along axis XX. Other motors which have afixed shaft in place of the screw may also be employed as described morefully in U.S. application Ser. No. 09/187,974, the disclosure of whichis incorporated herein by reference. As shown in the FIG. 12 embodimentthe nut 304 is rigidly interconnected to magnet 310 c and mountingcomponents 310 a, 310 b which are in turn fixedly mounted on the innerrace of upper rotational bearing 312 and lower rotational bearing 314for rotation of the nut 304 relative to housing 302 which is fixedlyinterconnected to the manifold 15 a of the injection molding machine.The axially driven screw 308 a is fixedly interconnected to valve pin 41which reciprocates 308 along axis X together with screw 308 a as it isdriven. As described more fully below, pin 41 is preferably readilydetachably interconnected to the moving component of the particularactuator being used, in this case screw 308 a. In the FIG. 22embodiment, the head 41 a of pin 41 p is slidably received within acomplementary lateral slot 321 provided in interconnecting component 320a. The housing 302 may be readily detached from manifold 15 a byunscrewing bolts 324 and lifting the housing 302 and sliding the pinhead 41 a out of slot 321 thus making the pin readily accessible forreplacement.

As can be readily imagined other motors may be employed which aresuitable for the particular flow control mechanism which is disposed inthe flow channel of the manifold or nozzle, e.g. valve pin or rotaryvalve. For example, motors such as a motor having an axially fixed shafthaving a threaded end which rotates together with the other rotatingcomponents of the actuator 301 and is screwably received in acomplementary threaded nut bore in pin interconnecting component 320, ora motor having an axially fixed shaft which is otherwise screwablyinterconnected to the valve pin or rotary valve may be employed.

Controlled rotation 318 of screw 308 a, FIG. 22, is achieved byinterconnection of the motor 300 a to a motor controller 316 which is inturn interconnected to the CPU, the algorithm of which (including PIDcontrollers) controls the on/off input of electrical energy to the motor300 a, in addition to the direction and speed of rotation 318 and thetiming of all of the foregoing. Motor controller 316 may comprise anyconventional motor control mechanism(s) which are suitable for theparticular motor selected. Typical motor controllers include aninterface 316 a for processing/interpreting signals received from thecomputer 20 similar to the interface 214 described with reference toFIGS. 9-11; and, the motor controllers typically comprise a voltage,current, power or other regulator receiving the processed/interpretedsignals from interface 316 a that regulates the speed of rotation of themotor 300 according to the instruction signals received from computer20.

FIG. 13 shows a pair of rotary valve flow controllers 200′ mounted in aheated manifold 15′ for distribution of fluid material from a mainbarrel injection channel 13′ to a common upstream distribution channel13 d having an axis Z to downstream channels 20 d having an axis X′ thatintersects the gates 9 a of mold cavity 9 i. As shown in FIG. 13, theaxis Z of upstream channel 13 d is not coaxial with the axis X′ ofdownstream channels 20 d. The rotary valves 200′ are disposed within theoff axis channel 13 d for controlling flow rate based on variablesindicative of sensor signals sent by downstream sensors 60 t, 80 t andreceived in some form by master computer controller 20 for use in acontrol algorithm. As shown in schematic form in FIG. 13, the rotaryvalves comprise a housing 206′ in which a plug 202′ is rotatablymounted. The plug has a central flow channel or bore 204′ which isrotatably alignable with feed bores 201′ provided within the body ofhousing 206′. Depending on the degree of rotational alignment of plugs202′ and channels 204′ with housing bores 201′, fluid will flow at avariable rate from channel 13 d through channels 204′ into non-coaxialdownstream channels/bores 20 d which lead to gates 9 a. Plugs 202′ arerotatable to a selected degree by drive mechanisms or actuators 110′,115′. Typically actuators 110′, 115′ comprise electric motors orelectrically powered actuators but can comprise any suitable actuatorfor effecting rotation of plugs 202′. The actuators 110′, 115′ areinterconnected to and receive command signals from computer controller20 which contains a control algorithm as described above for controllingthe degree of rotation of plugs 202′ and thus the rate of fluid flowduring an injection cycle in the same manner as described with referenceto the FIGS. 1-12 embodiments. As shown in FIG. 13, bore 204′ is in afully aligned, full open flow rotational position with respect todownstream channel 20 d wherein bore 204′, actuator 115′ and 208′ are atan intermediate point in an injection cycle which is in operating toregulate fluid flow; and, as shown in FIG. 13, bore 204″ is in a fullynot aligned, flow stop rotational position with respect to downstreamchannel 20 d′ wherein bore 204″, actuator 110′ and 208″ are at either acycle end/stop or cycle point in an injection cycle where flow isstopped.

Sensors 60 t and 80 t are mounted downstream of the rotary valves 200′and provide the fluid material condition data as variable inputs to thealgorithm of computer 20 in the same manner as described above tocontrol the operation of actuators 110′, 115′ during an injection cycle.As shown in FIG. 13, downstream channels 20 d include actuators 208′ andvalve pins 41′, 41″. Valve pins 41′, 41″ are interconnected to actuators208′ for reciprocal movement along axes X′ between open flow and closedflow positions wherein the distal ends of the valve pins 41′, 41″ closeoff the downstream channels 20 d at gate 9 a when moved to their fullydownstream direction by actuators 208 at the end of an injection cycle.As shown in FIG. 13, valve pin 41″ is in a fully downstream gate closedposition and valve pin 41′ is in its upstream open flow position. Theoperation of downstream actuators 208′ is similarly controlled by thealgorithm of computer 20 based on the sensor 60 t, 80 t signal data thatis sent to computer and used by the algorithm as a variable input. Aswith the embodiments described above, the downstream actuators 208′provide the function of opening and closing the gates at the beginningand end of an injection cycle while the upstream rotary valves 200′provide the function of controlling the rate of fluid flow during theinjection cycle between start and stop. As described above withreference to FIGS. 9-11, a flow rate profile can be predetermined andstored and the operation of rotary valves 200′ can then be controlled bycomputer 20 to emulate the predetermined flow rate profile that isstored in computer 20 or other memory communicating with the algorithmof computer 20.

FIG. 14 shows a valve pin 700 having a smooth outer surfaced curvilinearbulbous protrusion 750 for controlling melt flow from manifold channel760 to nozzle channel 710. The pin 700 is slidably mounted in nozzlechannel 710 having a distal extension section 720 having a tip end 730for closing off gate 740 when the pin is appropriately driven to theposition shown in FIG. 16. The pin 700, 830 is controllably slidablealong its axis Z. The bulbous protrusion 750 as shown in FIGS. 14, 14Ais in a flow shut-off position where the outer surface of a maximumdiameter section 755 of the bulb makes engagement contact with acomplementary shaped interior surface of the channel 765 sufficient toprevent melt flow 770 from passing through the throat section 766 whereand when the bulb surface 755 engages the inner surface 765 of the flowchannel. As perhaps best shown in FIG. 21, the bulb 750 has anintermediate maximum diameter section which is intermediate an upstreamsmooth curvilinear surfaced portion 820 and a downstream smoothcurvilinear surfaced portion 810. Melt flow 900 flowing under pressurefrom manifold or hotrunner channel 770 toward nozzle channel 710 passesthrough flow controlling passage 767. The melt flow is slower thenarrower passage 767 is and faster the wider that passage 767 is.Passage 767 may be controllably made narrower or wider by controlled CPUoperation of actuator 790 as described above with reference to otherembodiments via an algorithm which receives sensor variable signals froma sensor such as sensor 780. In the FIGS. 14-21 embodiments, the passage767 is gradually made wider and flow increased by downstream movement ofthe bulb 750 toward the gate 740. By contrast, in the FIG. 40 22embodiment, the passage 767 is made narrower by downstream movement ofthe bulb 750 from the position shown in FIG. 22 toward the throat 766restriction section, and made wider by upstream movement of the bulb 750away from the gate 740.

As shown in FIG. 21, the maximum diameter section typically has astraight surface 755 forming a cylindrical surface on the exterior ofthe bulb 750 having a diameter X. The throat 766 has a complementarystraight interior surface 765 in the form of a cylinder having the samediameter X as the surface 755. Thus as the bulb 750 is moved in anupstream direction (away from the gate), from the position shown in FIG.21, the flow controlling restriction 767 gets narrower and the melt flow900 is gradually slowed until the surface 755 comes into engagement withsurface 765 at which point flow is stopped at the throat 766. The samesequence of operation events occurs with respect to all of theembodiments shown in FIGS. 14-21. The maximum diameter surface 755 doesnot necessarily need to be cylindrical in shape. Surface 755 could be afinite circle which mates with a complementary diametrical circle onmating surface 765. The precise shape of surface 755 may be other thancircular or round; such surface 755 could alternatively be square,triangular, rectangular, hexagonal or the like in cross-section and itsmating surface 765 could be complementary in shape.

FIGS. 16, 16A show a third position where the end of the extended pincloses off flow through gate 740. FIGS. 14, 14A show a position whereflow 900 is shutoff at throat 766. FIGS. 15, 15A show a pin/bulbposition where flow 900 is being controlled to flow at a preselectedrate. Any one or more positions where the bulb surface 755 is further orcloser to surface 765 may be controllably selected by the CPU accordingto the algorithm resident in the CPU, the flow rate varying according tothe precise position of the bulb surface 755 relative to the matingsurface 765.

FIGS. 17, 18 show an embodiment where the pin does not have a distal endextension for closing off the gate 740 as the FIGS. 14-16 embodiment mayaccomplish. In such an embodiment, the algorithm for controlling flowdoes not have a third position for closing the gate 740.

FIGS. 19, 20A and 22 show an embodiment where the longitudinal aperture800 in which the pin 830 is slidably mounted in bushing or mount 810 hasthe same or a larger diameter than the maximum diameter surface 755 ofbulb 750. The aperture 800 extends through the body or housing of heatedmanifold or hotrunner 820 and thus allows pin 830 to be completelyremoved by backwards or upstream withdrawal 832. FIG. 19A, out of thetop end of actuator 790 for pin replacement purposes without thenecessity of having to remove mount or bushing 810 in order toreplace/remove pin 830 when a breakage of pin 830 may occur. The bushingor mount 810 is typically press fit into a complementary mountingaperture 850 provided in the body or housing of manifold or hotrunner820 such that a fluid seal is formed between the outer surface ofbushing or mount 810 and aperture 850. The central slide aperture forpin 830 extends the length of the axis of actuator 790 such that pin 830may be manually withdrawn from the top end of actuator 790.

As described above, the slidable back and forth movement of a pin 830having a bulb 750. FIGS. 14-22, is controllable via an algorithmresiding in CPU or computer, FIG. 17 which receives one or more variableinputs from one or more sensors 780.

The melt flow 900 is readily controllable from upstream channel 770 todownstream 710 channel by virtue of the ready and smooth travel of themelt over first the upstream smooth curvilinear surface 820 past themaximum diameter surface 755 and then over the smooth downstreamcurvilinear surface 810. Such smooth surfaces provide better controlover the rate at which flow is slowed by restricting passage 767 orspeeded up by making passage 767 wider as pin 830 is controllably movedup and down. The inner surface 765 of throat section 766 is configuredto allow maximum diameter surface 755 to fit within throat 766 upon backand forth movement of bulb 750 through throat 766.

1. A method of controlling the rate of flow of fluid through a flowchannel communicating with a gate of a mold in an injection moldingapparatus, the apparatus including a valve pin having a selectedlongitudinal length and a stem that is slidably mounted in an aperturein a housing body that is adapted for back and forth axial movement ofthe pin through the flow channel, the method comprising: forming the pinwith a protrusion at a selected position along its length such that theprotrusion is movable back and forth within the channel wherein theprotrusion has an upstream end and a downstream end; forming theprotrusion having upstream and downstream surfaces and a maximumdiameter outer circumferential surface between the upstream anddownstream surfaces; forming the mounting aperture for the stem with adiameter that is greater than or equal to the maximum diameter outercircumferential surface; forming the channel with an interior surfacearea portion which is complementary to the maximum diametercircumferential surface such that the maximum diameter outercircumferential surface of the protrusion is matable with the interiorsurface area portion of the channel to stop flow of the fluid throughthe channel; controlling movement of the pin through the channel toselectively position the upstream and downstream surfaces at positionseither further away from or closer to the interior surface area portionof the channel such that the fluid flow rate can be regulated bypositioning either the upstream or downstream surfaces further away fromor closer to the interior surface area portion of the channel.
 2. Themethod of claim 1 wherein the complementary interior surface areaportion of the channel is disposed at a position upstream of and awayfrom the gate of the mold.
 3. The method of claim 1 further comprisingcontrolling movement of the pin to position the downstream end of theprotrusion at controllably selectable distances relative to the interiorsurface area portion of the channel such that the rate of flow of fluidbetween the downstream end and the interior surface area portion iscontrollably variable.
 4. The method of claim 1 further comprisingcontrolling movement of the pin to position the upstream end of theprotrusion at controllably selectable distances relative to the interiorsurface area portion of the channel such that the rate of flow of fluidbetween the upstream end and the interior surface area portion iscontrollably variable.
 5. The method of claim 1 further comprising:sensing a selected condition of the fluid; controlling movement of thepin within the channel according to an algorithm that determines aposition for movement of the pin based on the use as a variable of avalue indicative of the selected condition of the fluid that is sensedin the step of sensing.
 6. The method of claim 1 further comprising:forming the aperture in the housing in which the pin is slidably mountedand the pin to have a diameter equal to or greater than the maximumdiameter circumferential surface of the protrusion of the pin. 7.Apparatus for controlling the rate of flow of fluid material through aninjection molding flow channel leading to a mold cavity, the apparatuscomprising: a pin having a longitudinal length and a stem slidablymounted in an aperture in a housing body that is adapted for back andforth axial movement of the pin through the flow channel; the pin havinga protrusion at a selected position along its length, the protrusionhaving an upstream surface and a downstream surface and a maximumdiameter circumferential surface intermediate the upstream anddownstream surfaces; the channel having an interior surface area portionwhich is complementary to the maximum diameter circumferential surfaceof the protrusion of the pin; the pin being slidable to a positionwithin the channel such that the maximum diameter circumferentialsurface of the protrusion is matable with the complementary interiorsurface portion of the channel to stop flow of the fluid material; thepin being movable axially back and forth to positions where both theupstream and downstream surfaces of the protrusion are positionableeither further away from or closer to the interior surface area portionof the channel, the fluid flow rate being regulated by positioning ofeither the upstream surface or the downstream surface relative to theinterior surface area portion of the channel.
 8. The apparatus of claim7 wherein the pin is drivable through at least a first position whereinfluid flow is stopped when the maximum diameter circumferential surfaceof the protrusion mates with the complementary interior channel surfaceand a second downstream or upstream position where fluid flow is enabledbetween either the upstream or downstream end of the protrusion and thecomplementary interior channel surface of the channel.
 9. The apparatusof claim 8 wherein the contour of the protrusion at the upstream ordownstream end of the protrusion is curvilinear.
 10. The apparatus ofclaim 8 wherein the contour of the protrusion at the upstream ordownstream end of the protrusion is curvilinear.
 11. The apparatus ofclaim 7 wherein the pin is adapted to be drivable through a downstreamposition where a terminal end of the pin downstream of the protrusionmates with a complementary exit aperture of the channel that isimmediately adjacent to an entrance port to the mold.
 12. The apparatusof claim 7 wherein the maximum diameter circumferential surface of theprotrusion is cylindrical in shape.
 13. The apparatus of claim 7 whereinthe complementary interior surface portion of the channel is cylindricalin shape.
 14. The apparatus of claim 7 wherein the aperture in thehousing in which the pin is slidably mounted has a diameter equal to orgreater than the maximum diameter circumferential surface of theprotrusion of the pin.
 15. The apparatus of claim 7 wherein thecomplementary interior surface portion of the channel is disposedupstream of a gate area of the mold, the pin being adapted toselectively position the protrusion relative to the complementaryinterior surface portion of the channel such that the rate of flow ofthe fluid is controllably varied.
 16. The apparatus of claim 7 furthercomprising: a sensor for sensing a selected condition of the fluid; acomputer interconnected to the sensor for receiving a signalrepresentative of the selected condition sensed by the sensor, thecomputer including an algorithm utilizing a value corresponding to thesignal received from the sensor as a variable for controlling operationof an actuator that is drivably interconnected to the pin.
 17. Theapparatus of claim 7 wherein the pin comprises a first portion having adiameter complementary to the aperture in the housing and a secondportion interconnecting the first portion and the protrusion, the secondportion having a maximum diameter that is less than the diameter of thefirst portion and the maximum diameter of the protrusion.